(1) Field of the Invention
The present invention relates to new and improved submarine pressure hull structures which provide acoustically isolated hull openings. More particularly, the present invention relates to new and improved submarine hull structures having notable utility in providing acoustically isolated torpedo tube openings for launching torpedoes and the like and acoustically isolated shaft openings for supporting operating shafts and other rotary shafts which extend through the pressure hull.
(2) Description of the Prior Art
Torpedo tube openings are conventionally provided by two coaxial structural members, an outer tubular insert welded to the submarine pressure hull and an inner torpedo tube welded to the outer hull insert. Because of the rigid welded structure, noise and vibration generated by the torpedo ejection system are transmitted directly to the submarine hull.
Similarly, hull structures conventionally provided for supporting operating shafts and other rotary shafts which extend through the pressure hull transmit shaft generated vibrations and shaft transmitted noise directly to the submarine pressure hull via the shaft support structure including the usual shaft stuffing box.
Submarines are primarily detected by acoustic sensing systems which listen passively for any sound generated by the submarine, therefore reducing the transmission of vibrations and other noise to the submarine pressure hull is of critical importance in submarine design.
In prior art submarine systems, elastomeric materials are used around the launch tube structures to minimize propagatin of launch noise to the hull of the submarine. At great depths, pressure acting on the launch tubes can cause breakdown of the elastomeric damping materials. Resulting forces on the launch tube can cause the tube to be pushed through the hull insent. The same problems exist with shafts that pass through the submarine's pressure hull.